What is the best way to use two 27" monitors on your desk?

You don't say what you'll be using them for. I'm (among other things) a programmer, and for me being able to see a tall vertical area in my text editor is of primary importance. Thus, given 2 widescreen monitors, I'd set them up vertically, next to each other.

I'm not unique here: when I visited Google, most of the programmers I saw had this layout too.

I would think this could help with your neck problem, since it makes the display area closer to a square, and not a really wide rectangle. Alternatively, you could keep them horizontal, and stack one right above the other. Depends on the shape of the things you're going to be looking at most, I guess!

Honestly, I've been using 2 24inch monitors for years (one 24ich connected to my 24inch iMac). I personally think using two monitors is not necessary anymore, if you effectively use spaces/virtual desktops.

I now only use my 24inch iMac as my only display, and basically just got used to the new setup, while mastering the keyboard shortcuts. I don't need to move my head, the OS does it for me.

I say ditch the other monitor and get use to using cntrl+arrow keys, just my opinion.

Make sure both are at the same height, if you still have neck strain, then you are not sitting at the right level:

(image courtesy of this link).

If you put them higher or lower, you’ll have to adjust with your neck, thus causing strain.

An excellent blog post about that was written by our own creator…

LCD Monitor Arms. Good old school post.